Hydrogen peroxide is typically manufactured by a process known as autoxidation, which produces hydrogen peroxide at about 70% by weight concentration through an energy intensive distillation stage. Because most hydrogen peroxide commercial applications use low hydrogen peroxide concentrations (about 15% by weight), the 70% by weight hydrogen peroxide solution must be diluted prior to storage and use. End users have increasingly become interested in the concept of on-site, on-demand hydrogen peroxide generation to reduce transportation costs, storage, and concentration dilution costs. However, combining H2 and O2 in conventional reactor systems is difficult at H2 concentrations above about five percent by weight, as the mixture becomes flammable and even explosive. At low H2 concentrations, the rate of H2 diffusion in the liquid phase is extremely slow, thus necessitating the use of very high pressures, and rendering the process energy inefficient. The solubility of H2 in the liquid phase can be improved by adding H2SO4 and halide ions, but both pose serious corrosion and contamination problems.
The present invention provides a solution to these problems. With the present invention it is possible to provide on-site direct combination of H2 and O2 using a microchannel reactor. This reactor possesses a high surface-to-volume ratio and exhibits enhanced heat and mass transfer rates. In one embodiment, the microchannel reactor allows for H2 concentrations above about five percent by weight without the risk of explosion, while providing a low-pressure, energy-efficient operation that is safe.